code: def __len__(self):
      return len(self.history)
  
file_path: opacus/opacus/accountants/rdp.py
imports: from typing import List, Optional, Tuple, Union
  from .accountant import IAccountant
  from .analysis import rdp
label_desc: Use image node_id 5 for calling the RDPAccountant obj's underlying member method code with example usage: obj.__len__() and returns: len